A manufacture of sophisticated apparatus such as jet engines requires multiple sequential machining operations. Close tolerances must be maintained and it is of course important to efficiently carry out the overall machining process. At one time separate machines were used for drilling, milling, etc. each requiring a new setup as the workpiece was moved to the new machine.
Machining centers are now conventionally used which are computer controlled and where with one set up the tools are changed with instructions from a numerical control program that automatically changes tools and stores them within the machining center. The sequential operations are thereby more efficiently carried out and errors in the repeated setup process reduced.
Grinding, however, has continued to be a problem and conventionally is not included in the machining center. Conventional grinding wheels have grit discharged from the wheel which can clog up and interfere with the cooling and lubricating system of the machining center. The use of superabrasive wheels such as those of cubic boron nitrite with a steel core and one layer of grit secured to the core with nickel plate has avoided the grit problem, but difficulties in the setup remain. Such wheels require coolant and cleaning fluids to be delivered in proper amounts at proper locations. The process of setting up cooling and cleaning nozzles as dictated by research of super abrasive machining to maximize tool performance is very labor intensive and has not been in wide use in a production environment. This coupled with the hazard of hanging cooling lines has made this an impractical step. Accordingly, it has been conventional to remove the workpiece from the machining center to a separate grinding machine where there is not only a disruption in the flow of material, and a time loss in setting up the new machine, but variations in the setup may produce less than optimum results.